Artificial chemokines: combining chemistry and molecular biology for the elucidation of interleukin-8 functionality.
How can we understand the contribution of individual parts or segments to complex structures? A typical strategy to answer this question is simulation of a segmental replacement followed by realization and investigation of the resulting effect in structure-activity studies. For proteins, this problem is commonly addressed by site-directed mutagenesis. A more general approach represents the exchange of whole secondary structure elements by rationally designed segments. For a demonstration of this possibility we identified the alpha-helix at the C-terminus of human interleukin-8 (hIL-8). Since this chemokine possesses four conserved cysteine residues, it can easily be altered by ligation strategies. A set of different segments, which are able to form amphiphilic helices, was synthesized to mimic the C-terminal alpha-helix. Beside sequences of alpha-amino acids, oligomers of non-natural beta(3)-amino acids with the side chains of canonical amino acids were introduced. Such beta-peptides form helices, which differ from the alpha-helix in handedness and dipole orientation. Variants of the semisynthetic hIL-8 proteins demonstrated clearly that the exact side chain orientation is of more importance than helix handedness and dipole orientation. The activity of a chimeric protein with a beta-peptide helix that mimics the side chain orientation of the native alpha-helix most perfectly is comparable to that of the native hIL-8. Concepts like this could be a first step toward the synthesis of proteins consisting of large artificial secondary structure elements.
David
Ralf
R
Institut für Biochemie, Fakultät für Biowissenschaften, Pharmazie and Psychologie, Universität Leipzig, Brüderstrasse 34, D-04103 Leipzig, Germany.
Günther
Robert
R
Baumann
Lars
L
Lühmann
Tessa
T
Seebach
Dieter
D
Hofmann
Hans-Jörg
HJ
Beck-Sickinger
Annette G
AG
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D002942:Circular Dichroism; D020650:Combinatorial Chemistry Techniques; D006801:Humans; D006820:Hyaluronic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D016209:Interleukin-8 / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008967:Molecular Biology; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D023062:Receptors, Interleukin-8A / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
D016209:Interleukin-8; D023062:Receptors, Interleukin-8A; D011994:Recombinant Proteins; D006820:Hyaluronic Acid